UV‐C irradiation delays browning of fresh‐cut “Fuji” apples
Junwei Yuan, Haifen Wang, Yusheng Li, Lan Chen, Yanli Zheng, Yuqian Jiang, Yao Tang, Xihong Li, Jixin Li, Luyin Wang
Abstract
In order to explore the effect and the corresponding physiological mechanisms of UV-C irradiation on browning of fresh-cut apples, both whole and sliced apple were irradiated with UV-C (254 nm) for 5 min before or after processing. The browning index (BI) of slices was immediately measured, while other relevant physiological parameters were evaluated on quick-frozen samples during refrigerated storage. Results indicated that both pre- and post-processing UV-C treatments effectively delayed browning of apple slices; nevertheless, post-processing UV-C treatment was more efficient. BI significantly negatively correlated with non-enzymatic capacities, and activities of catalase, ascorbate peroxidase, and glutathione reductase (GR). BI was positively correlated with the contents of H2O2 and malondialdehyde (MDA). These findings suggested that UV-C treatment delayed browning of apple slices during cold storage by improving the antioxidant system. Post-processing UV-C treatment was more efficient than pre-processing. Practical applications UV-C treatment is a technique of preservation for fresh-cut fruits. It is widely applied in food processing and many other fields due to its convenience, safety, low cost, etc. In the present study, both pre- and post-processing UV-C (254 nm) irradiation for 5 min could (1) delay the browning of fresh-cut apple, (2) improve the polyphenol oxidase activity and reduce the phenylalanine ammonia-lyase (PAL) activity and total phenolic content (TPC), and (3) reduce the accumulation of H2O2 and malondialdehyde, and increase the antioxidant activities of fresh-cut apples. Thus, UV-C treatments maintain the fresh-cut quality of fresh-cut apple slices and extend their shelf life.